1. Field of the Invention
The invention relates to polymeric polyesters and more particularly relates to water-soluble polymeric polyesters which are the condensation product of a polyoxyalkylene glycol and the addition product of a dimer fatty acid and maleic anhydride.
2. Brief Description of the Prior Art
In view of rapidly changing environmental, governmental and handling considerations and the growing shortage of petroleum base supplies, water-soluble lubricant products are gaining importance to the economy of the United States. Representative of prior art descriptions of water-soluble lubricant products is the description found in U.S. Pat. No. 3,769,215. In general, water-soluble lubricant products heretofore available have not been entirely satisfactory in all respects. For example, when employed in aqueous hydraulic systems, relatively high viscosity enhancement may not be achieved as desired.
The polyester compositions of the present invention exhibit a substantial thickening effect on the water in aqueous hydraulic systems when added thereto, providing the aqueous system with a higher viscosity with enhanced shear stability. Viscosities can be obtained in aqueous hydraulic systems employing the polyesters of the present invention as additives, approaching the viscosities of oil based hydraulic systems, i.e.; 40-80 cSt, at 38.degree. Centigrade.